A power supply device that includes a plurality of electricity storage elements each including lead terminals; a conductive connector connected to the lead terminals; a circuit board including a conductive path; a conductive relay terminal electrically connected to the conductive path, the connector being disposed so as to be in contact with the relay terminal; and a resin holder configured to hold the plurality of electricity storage elements, wherein the holder includes an electricity storage element holder configured to hold the electricity storage elements, a connecting member holder configured to hold the connector, and a fitting groove into which the lead terminals can be fitted, and the connecting member holder is formed so as to traverse the fitting groove.